A drive unit having an engine and a transmission having a variable transmission ratio is present, for example, in today's typical motor vehicles. Transmissions having a plurality of driving positions, i.e., gears, are used as transmissions. The intended power output may be expressed, for example, by the angular position of a gas pedal and normally corresponds to an intended torque. The setpoint power output quantity may be the setpoint output torque of the drive unit which is to act upon the wheels of the motor vehicle. The actual output torque is generated by appropriate control and/or regulation on the basis of the setpoint output torque. It is understood that here and hereinafter the term “intended power output” means not only a desired power output or a desired torque, but also further quantities which affect the operation of the internal combustion engine.
In automatic transmissions, for reasons of comfort, it is desirable that, when shifting from one driving position or one gear to another without changing the intended power output, the output torque applied to the wheels of the motor vehicle is not also changed to avoid a “shifting jolt.” German Published Patent Application No. 43 33 899, for example, describes a method for achieving this object. German Published Patent Application No. 42 04 401 also describes a method for avoiding the shifting jolt when shifting gears.
However, consistent implementation of this method in certain situations may result in more power being generated than necessary for operating the vehicle when the driver intends to stop the vehicle. The reason for this is that the minimum possible output torque of the drive unit varies abruptly from one gear to another. This minimum possible output torque—a braking torque in most operating situations of a motor vehicle—may therefore not be achieved if an abrupt torque jump is to be completely suppressed in shifting gears. In other words, after shifting, possibly more fuel is injected than absolutely necessary, even if the driver does not step on the gas pedal. To nevertheless brake the vehicle as desired, the driver would have to actuate the brake, which in turn increases its wear.